Syndromic surveillance was performed during the G8 Summit held in Fukuoka and Miyazaki City in July 2000. Any case suspected as acute infectious disease was reported from designated medical facilities. Those cases were categorized in 5 clusters including "hemorrhagic and skin symptoms", "respiratory symptoms", "gastroenteric symptoms", "neural symptoms", and "miscellaneous symptoms". To compare how closely these incidence trends were representing those of the infectious disease surveillance, these results were analyzed for two weeks. In Miyazaki, duplicated report were accepted when more than one symptom were found. The ratio of weekly reported number for each cluster was calculated for two weeks, and then the ratio for former/latter week was calculated for each cluster. The results from Fukuoka and Miyazaki surveillance revealed the average former/latter ratio +/- SD = 0.99 +/- 0.292, 95% CI; 0.71-1.28 and 1.19 +/- 0.298, 0.93-1.45, respectively. These results indicate that syndromic surveillance is well represented with the infectious disease surveillance trends. Single reporting, employed in Fukuoka, was easier for analysis. Reported number for acute respiratory syndrome was larger than that of infectious disease surveillance, indicating that the latter could not detect non-reportable adult cases. Syndromic surveillance enables us to show the trend quickly and it can be carried out with smaller costs and human resources. This study concluded that a syndromic surveillance is effective for such high-profile events, but sometimes it is hard to analyze the trend accurately, because of insufficient period of baseline data, number and size of the reporting sentinel facilities.